Vulnerability Description
SiYuan before v3.7.2 contains a missing authorization vulnerability in the POST /mcp kernel endpoint, which is gated only by a general auth check (model.CheckAuth) with no admin-role or read-only enforcement. This exposes 31 MCP tools, including a file tool with list/read/write/delete/rename/copy actions across the entire workspace. When the Publish server is enabled in anonymous mode (Conf.Publish.Enable=true and Conf.Publish.Auth.Enable=false), the Publish reverse proxy attaches an anonymous RoleReader JWT to proxied requests, allowing a remote unauthenticated attacker to reach /mcp. The attacker can read conf/conf.json to extract accessAuthCode, api.token, and cookieKey in plaintext, write arbitrary files in the workspace, and plant a plugin into data/plugins/ that executes with nodeIntegration:true and no contextIsolation on the next desktop launch, leading to administrator takeover.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/siyuan-note/siyuan/commit/c72ca4cd09019e5f64afdee8f8c6ec5ef34
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8
- https://www.vulncheck.com/advisories/siyuan-before-unauthenticated-administrator
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8
FAQ
What is CVE-2026-66012?
CVE-2026-66012 is a vulnerability with a CVSS score of 10.0 (CRITICAL). SiYuan before v3.7.2 contains a missing authorization vulnerability in the POST /mcp kernel endpoint, which is gated only by a general auth check (model.CheckAuth) with no admin-role or read-only enfo...
How severe is CVE-2026-66012?
CVE-2026-66012 has been rated CRITICAL with a CVSS base score of 10.0/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-66012?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.